Derive substantive findings on pulmonary function and relate these findings to genetic and environmental risk factors for chronic obstructive pulmonary disease (COPD). The length of follow-up, the vast array of family data available, and the presence of several genetic marker test results make the Baltimore Longitudinal Study uniquely satisfactory to help clarify the familial component in the etiology of COPD, as well as to explore the biological, medical, and related disease characteristics, detectable in living subjects, which might be associated with patterns of aging and mortality.